Effects of Steam Explosion Pretreatment at Different Severity Factors on the Structure, Chemical Composition, and Digestive Properties of Dendrobium officinale (Tiepishihu) Polysaccharides

 

Introduction

Dendrobium officinale (commonly known as Tiepishihu) is a traditional medicinal orchid highly valued for its polysaccharides, which exhibit immunomodulatory, antioxidant, anti-inflammatory, and gut health-promoting activities. However, the structural rigidity of its polysaccharides and the dense plant matrix can limit extraction efficiency and bioavailability. Steam explosion (SE) pretreatment, a hydrothermal method combining high-pressure saturated steam and sudden decompression, has emerged as an efficient technique for cell wall disruption and modification of biopolymers. Investigating the effect of different severity factors (combining temperature, pressure, and residence time) on polysaccharide properties can provide insights into optimizing functionality for nutraceutical and pharmaceutical applications.

Meaning of Steam Explosion Pretreatment

Steam explosion involves subjecting plant biomass to high-pressure steam for a controlled duration, followed by a sudden release to atmospheric pressure. This causes:

  • Cell wall rupture due to shear and thermal forces.

  • Partial hydrolysis of hemicellulose and lignin.

  • Structural modification of polysaccharides, improving solubility and digestibility.

The severity factor (log R₀) is a key index that integrates pretreatment conditions:

log⁡R0=log⁡[t×exp⁡(T−10014.75)]\log R_0 = \log \left[ t \times \exp \left(\frac{T-100}{14.75}\right)\right]

where t is time (min) and T is temperature (°C).

Structural Effects

  • Low severity SE: Causes moderate cell wall disruption, leading to higher extraction yield of intact polysaccharides.

  • Medium severity SE: Promotes depolymerization, decreases molecular weight, and increases solubility. FTIR and NMR analyses show partial cleavage of glycosidic linkages and exposure of functional groups.

  • High severity SE: Results in excessive degradation, reducing structural integrity, causing browning due to Maillard reactions, and altering polysaccharide branching patterns.

Chemical Composition Changes

  • Monosaccharide profile: SE alters the ratio of glucose, mannose, galactose, and arabinose in D. officinale polysaccharides. Moderate severity enhances the release of bioactive mannose- and galactose-rich fractions.

  • Molecular weight distribution: Decreases with higher severity, shifting from high-molecular-weight biopolymers to oligosaccharides.

  • Phenolic and lignin content: Reduced under SE, improving polysaccharide purity.

  • Degree of esterification and uronic acids: Higher severity increases free uronic acids, enhancing solubility and potential antioxidant activity.

Digestive Properties

  • In vitro digestibility: SE-treated polysaccharides show lower resistance to simulated gastric and intestinal digestion compared to untreated samples, enhancing release of reducing sugars.

  • Prebiotic potential: Medium severity SE enhances fermentability by gut microbiota, promoting short-chain fatty acid (SCFA) production (acetate, propionate, butyrate).

  • Bioavailability: Modified polysaccharides with lower molecular weight exhibit better absorption and gut regulatory functions.

  • Excessive degradation (high severity) may lower biological activity by destroying functional motifs.

Advantages of Steam Explosion Pretreatment

  • Eco-friendly (no harsh chemicals).

  • Enhances extraction yield and efficiency.

  • Improves solubility and functional activity.

  • Increases gut fermentability of polysaccharides.

Disadvantages

  • Over-treatment may cause excessive depolymerization.

  • Possible loss of bioactivity at very high severity factors.

  • Risk of browning and unwanted side reactions.


Conclusion

Steam explosion pretreatment significantly influences the structural, chemical, and digestive properties of Dendrobium officinale polysaccharides in a severity-dependent manner. Moderate severity factors optimize yield, solubility, and prebiotic effects, while excessively high severity may reduce bioactivity through degradation. Understanding these relationships is crucial for tailoring polysaccharide functionality in functional foods, nutraceuticals, and therapeutic formulations.

Summary

Steam explosion pretreatment modifies Dendrobium officinale polysaccharides by altering their structure and composition, leading to improved solubility, digestibility, and gut health potential. Optimal severity enhances functional properties, while over-treatment compromises quality.

Comments

Post a Comment

Popular posts from this blog

Complexity

Image
1. General Definition Complexity describes systems, phenomena, or problems characterized by multiple interacting components, unpredictability, and often emergent behavior. These systems resist simplification and require holistic approaches to understanding and managing. 2. Characteristics of Complexity a. Interdependence The parts or elements within the system are interdependent, meaning the behavior of one part affects others. This interconnectedness often creates cascading effects. b. Emergence Complex systems display properties or behaviors that are not present in their individual components but emerge from their interactions. For instance, consciousness arises from neural interactions in the brain. c. Nonlinearity Outcomes are not proportional to inputs, and small changes in one part of the system can lead to disproportionate effects elsewhere (butterfly effect). This makes prediction difficult. d. Dynamism Complex systems are dynamic, constantly evolving due to interactions among ...
Read more
Image
 International Research Excellence Best Paper Awards Website link:  https://bestpaperawards.com/ # Social Sciences # Psychology #Arts # Psychology #Agriculture #Science
Read more

Research Training and Scholarly Activity during General Pediatric Residency in Canada

Image
                        Research training and scholarly activity are integral components of general pediatric residency programs in Canada. They ensure that residents are well-equipped with the skills needed to critically evaluate and conduct research, which in turn contributes to the advancement of pediatric healthcare. Here are some key points and aspects of this training: Structure of Research Training Research Curriculum : Many residency programs include a structured curriculum that covers essential topics such as research methodology, biostatistics, epidemiology, and ethics in research. Workshops and Seminars : Regular workshops and seminars on research design, data analysis, and scientific writing are commonly part of the training. Protected Research Time : Programs often provide protected time during the residency for residents to focus on their research projects, ensuring they can dedicate sufficient time to their schol...
Read more